RTC is 24 bit width and k_timer is 64 bit. It is hard to test corner
cases but RTC hardware feature can help here. There is a task which
moves counter to 0xfffff0 which is close to overflow. However, there
is an internal driver state that also needs to be aligned to shift
the time properly. Adding optional function which triggers overflow
and updates internal state. This can be used for testing corner cases.
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>